如何格式化具有多个对象返回的json结构？ （动态）

Question

I have an API call and it returns like this:

{
    "result": {
        "720268538": {
            "icon_url": "-9a81dlWLwJ2UUGcVs_nsVtzdOEdtWwKGZZLQHTxDZ7I56KU0Zwwo4NUX4oFJZEHLbXU5A1PIYQNqhpOSV-fRPasw8rsUFJ5KBFZv668FFEuh_KQJTtEuI63xIXbxqOtauyClTMEsJV1jruS89T3iQKx_BBqa2j3JpjVLFH1xpp0EQ",
            "icon_url_large": "",
            "icon_drag_url": "",
            "name": "Chroma Case",
            "market_hash_name": "Chroma Case",
            "market_name": "Chroma Case",
            "name_color": "D2D2D2",
            "background_color": "",
            "type": "Base Grade Container",
            "tradable": "1",
            "marketable": "1",
            "commodity": "1",
            "market_tradable_restriction": "7",
            "fraudwarnings": "",
            "descriptions": {
                "0": {
                    "type": "html",
                    "value": " ",
                    "app_data": ""
                },
                "1": {
                    "type": "html",
                    "value": "Container Series #38",
                    "color": "99ccff",
                    "app_data": ""
                },
                "2": {
                    "type": "html",
                    "value": " ",
                    "app_data": ""
                },
                "3": {
                    "type": "html",
                    "value": "Contains one of the following:",
                    "app_data": ""
                },
                "4": {
                    "type": "html",
                    "value": "Glock-18 | Catacombs",
                    "color": "4b69ff",
                    "app_data": ""
                },
                "5": {
                    "type": "html",
                    "value": "M249 | System Lock",
                    "color": "4b69ff",
                    "app_data": ""
                },
                "6": {
                    "type": "html",
                    "value": "MP9 | Deadly Poison",
                    "color": "4b69ff",
                    "app_data": ""
                },
                "7": {
                    "type": "html",
                    "value": "SCAR-20 | Grotto",
                    "color": "4b69ff",
                    "app_data": ""
                },
                "8": {
                    "type": "html",
                    "value": "XM1014 | Quicksilver",
                    "color": "4b69ff",
                    "app_data": ""
                },
                "9": {
                    "type": "html",
                    "value": "Dual Berettas | Urban Shock",
                    "color": "8847ff",
                    "app_data": ""
                },
                "10": {
                    "type": "html",
                    "value": "Desert Eagle | Naga",
                    "color": "8847ff",
                    "app_data": ""
                },
                "11": {
                    "type": "html",
                    "value": "MAC-10 | Malachite",
                    "color": "8847ff",
                    "app_data": ""
                },
                "12": {
                    "type": "html",
                    "value": "Sawed-Off | Serenity",
                    "color": "8847ff",
                    "app_data": ""
                },
                "13": {
                    "type": "html",
                    "value": "AK-47 | Cartel",
                    "color": "d32ce6",
                    "app_data": ""
                },
                "14": {
                    "type": "html",
                    "value": "M4A4 | 龍王 (Dragon King)",
                    "color": "d32ce6",
                    "app_data": ""
                },
                "15": {
                    "type": "html",
                    "value": "P250 | Muertos",
                    "color": "d32ce6",
                    "app_data": ""
                },
                "16": {
                    "type": "html",
                    "value": "AWP | Man-o'-war",
                    "color": "eb4b4b",
                    "app_data": ""
                },
                "17": {
                    "type": "html",
                    "value": "Galil AR | Chatterbox",
                    "color": "eb4b4b",
                    "app_data": ""
                },
                "18": {
                    "type": "html",
                    "value": "or an Exceedingly Rare Special Item!",
                    "color": "ffd700",
                    "app_data": ""
                },
                "19": {
                    "type": "html",
                    "value": " ",
                    "app_data": ""
                },
                "20": {
                    "type": "html",
                    "value": "",
                    "color": "00a000",
                    "app_data": {
                        "limited": "1"
                    }
                }
            },
            "owner_descriptions": "",
            "tags": {
                "0": {
                    "internal_name": "CSGO_Type_WeaponCase",
                    "name": "Container",
                    "category": "Type",
                    "category_name": "Type"
                },
                "1": {
                    "internal_name": "set_community_6",
                    "name": "The Chroma Collection",
                    "category": "ItemSet",
                    "category_name": "Collection"
                },
                "2": {
                    "internal_name": "normal",
                    "name": "Normal",
                    "category": "Quality",
                    "category_name": "Category"
                },
                "3": {
                    "internal_name": "Rarity_Common",
                    "name": "Base Grade",
                    "category": "Rarity",
                    "color": "b0c3d9",
                    "category_name": "Quality"
                }
            },
            "classid": "720268538"
        },
        "success": true
    }
}

Result can have multiple returns I was wondering how the struct should look, this is what I have so far but it returns like nothing.

type AssetInfo struct {
    Result `json:"result"`
}

type Result struct {
    Asset   map[string]Asset `json:"asset"`
    Success bool             `json:"success,omitempty"`
}

type Asset struct {
    IconUrl           string                   `json:"icon_url,omitempty"`
    IconUrlLarge      string                   `json:"icon_url_large,omitempty"`
    IconDragUrl       string                   `json:"icon_drag_url,omitempty"`
    Name              string                   `json:"name,omitempty"`
    MarketHashName    string                   `json:"market_hash_name,omitempty"`
    MarketName        string                   `json:"market_name,omitempty"`
    NameColor         string                   `json:"name_color,omitempty"`
    BGColor           string                   `json:"background_color,omitempty"`
    Type              string                   `json:"type,omitempty"`
    Tradable          string                   `json:"tradable,omitempty"`
    Marketable        string                   `json:"marketable,omitempty"`
    Commodity         string                   `json:"commodity,omitempty"`
    TradeRestrict     string                   `json:"market_tradeable_restriction,omitempty"`
    FraudWarnings     string                   `json:"fraudwarnings,omitempty"`
    Descriptions      map[string]*Descriptions `json:"descriptions,omitempty"`
    OwnerDescriptions string                   `json:"owner_descriptions,omitempty"`
    Tags              map[string]*Tags         `json:"tags,omitempty"`
    ClassId           string                   `json:"classid,omitempty"`
}

type Descriptions struct {
    Type    string `json:"type"`
    Value   string `json:"value"`
    Color   string `json:"color,omitempty"`
    AppData string `json:"appdata"`
}

type Tags struct {
    InternalName string `json:"internal_name"`
    Name         string `json:"name"`
    Category     string `json:"category"`
    Color        string `json:"color,omitempty"`
    CategoryName string `json:"category_name"`
}

If anybody could tell me what's wrong with my struct that would be great thanks.

The thing that confuses me is like how Descriptions returns not an array but multiple objects that could range from 0-20 how do I prepare a struct for this when I don't know how many objects are going to return, as well result can return multiple "720616831" so how should this look?

Answer 1

You're going to kick yourself for the first mistake -- your JSON has result but your struct tag has response.

The second problem is a trickier one. The thing is that you declared that your Asset map is nested inside the result as a key called "asset", but that's not true. Actually it's just all of the keys of the result other than success/error. Unfortunately, encoding/json doesn't have any way to express this. You can say that result is a map[string]interface{}, and then success/error if they exist will be bool/string, and the assets will be more map[string]interface{}s containing keys for all of the other fields. That works, but it's a bit ugly/inefficient, and a lot of work if you want to convert into a proper struct type so that you can have methods on it.

Maybe a better way to go is to decode into this type:

type AssetIntermediate struct {
    Result map[string]json.RawMessage `json:"result"`
}

as well as having

type Asset struct { /* all those fields */ }
type AssetInfo struct {
    Success bool
    Error string
    Assets map[string]Asset
}

Then you can do

var intermediate AssetIntermediate
err := json.Unmarshal(data, &intermediate)
/* handle err */

var ai AssetInfo

/* At this point, intermediate.Result is a map
 * of strings to json.RawMessage, which is just a []byte
 * containing not-yet-decoded JSON. We want to take
 * each field and put it into ai where it belongs.
 */
for k, v := range intermediate.Result {
    var err error
    // error and success keys are decoded into the respective fields
    if k == "error" {
        err = json.Unmarshal(v, &ai.Error)
    } else if k == "success" {
        err = json.Unmarshal(v, &ai.Success)
    } else {
        // Otherwise, we have an asset. First decode it...
        var asset Asset
        err = json.Unmarshal(v, &asset)
        if err == nil {
            // Create the Assets map if it doesn't exist yet
            if ai.Assets == nil {
                ai.Assets = map[string]Asset{}
            }
            // And store the asset in the map under the key k.
            ai.Assets[k] = asset
        }
    }
    /* handle err if non-nil */
}

which is a lot more work than a single Decode call, but it should basically do the right thing.

If all of this is inside a function that returns (*AssetInfo, error) then the right thing to put in place of /* Handle err */ might be

if err != nil {
    return nil, err
}